Non-metallic mine pressure fuse

ABSTRACT

A non-metallic mine pressure fuse, having a housing comprising upper and lower portions secured together, a leaf spring with its peripheral surface retained between the upper and lower housing portions and its central portion projecting upwardly in the unbiased state, a percussion pin supported for axial displacement relative to the housing and retained at a central aperture provided therefor in the leaf spring so as to penetrate a percussion explosive charge in the lower housing upon flexing of the leaf spring to a downwardly projecting position, a trip member projecting from the upper surface of the housing and arranged for axial displacement relative thereto, and a pressure translating member interposed between the trip member and the leaf spring to cause a downward flexing of the spring upon an external pressure in excess of a predetermined value applied to the trip member, wherein detent means are provided to prevent restoration of the pressure translating member to its initial position prior to the exertion of a pressure of lesser magnitude than the predetermined value.

United States Patent Becker Oct. 17, 1972 Primary Examiner-Samuel W.Engle Attorney-Craig, Antonelli & Hill [72] Inventor: Franz Becker,Bonn, Germany [57] ABSTRACT [73] Asslgnee: g Nobel Akhengeseuschah Anon-metallic mine pressure fuse, having a housing rolsdorf, Germanycomprising upper and lower portions secured {22] Filed: June 13, 1969together, a leaf spring with its peripheral surface retained between theupper and lower housing por- [21 1 Appl 833025 tions and its centralportion projecting upwardly in the unbiased state, a percussion pinsupported for axial [30] Foreign Application Priority Data displacementrelative to the housing and retained at a g 1 1968 Germany up 17 71 9356central aperture provided therefor in the leaf spr ng so as to penetratea percussion explosive charge In the lower housing upon flexing of theleaf spring to a Zll "mi/823125;: downwardly projecting position, a tripmember [58] i 70 79 73 jecting from the upper surface of the housing andar- 0 ranged for axial displacement relative thereto, and a pressuretranslating member interposed between the [56] Reerences Cited tripmember and the leaf spring to cause a downward UNITED STATES PATENTSflexing of the spring upon an external pressure in excess of apredetermlned value applied to the trip 2,488,547 ll/l949 Llcuegren..lO2/8 member, wherein detem means are provided to 2,598,157 5/1952Everett ..l02/79 prevent restoration of the pressure translating member2,857,842 10/1958 Malm ..i02/8 to its initial position prior to theexertion of a pressure 2,923,237 2/1960 Bletkamp, ll 102/8 f lessermagnitude than the predetermined value. 3,392,47l 7/1968 Foote ..42/l0 X9 Claims, 1 Drawing Figure i 35 i I 5 41 39 ,1 5 6o ,1 5 t I l4 M A I 8v l3 h u T3 T M. 9 fir:

'\ fifi''l i 1 i L z Jf g 3'59! PATENTEDUET 17 m2 1 m w M 5 M M LVN w 33 INVENTOR FRANZ BECKER W Mr ATTORNEYS NON-METALLIC MINE PRESSURE FUSEBACKGROUND OF THE INVENTION The present invention relates to anon-metallic mine pressure fuse or detonator, having a housing includingupper and lower portions secured together, a percussion pin disposed, inan axially-displaceable manner, in the upper portion of the housing withits tip extending, through a leaf spring, with which it is secured forconjoint axial displacement, and a trip member projecting out of theupper portion of the housing and operatively connected with the leafspring to cause a downward flexing of the spring, and a correspondingdepression of the percussion pin into a percussion explosive charge,upon application of an external pressure, in excess of a predeterminedvalue, upon the trip member.

In conventional non-metallic mine pressure fuses or detonators of thetype described above, the percussion pin can be actuated by means of anintermediate pressure translating member causing a downward flexing ofthe leaf spring. This pressure or force translating member is positionedwithin the upper portion of the housing and adapted for axialdisplacement therein. At its lowermost portion, the member is adapted toengage the leaf spring by means of beads or other projections disposedso as to cooperate with the leaf spring between the peripheral rim andthe center thereof. The beads or other projections are generallyprovided in an annular manner or in another arrangement wherein thepoints of contact between the pressure translating member and the leafspring are spaced equidistant from the center of the spring.

It has been known heretofore to interpose a pressure translating memberbetween a leaf spring and a trip or trigger member, which is guided inthe upper portion of the housing by means of a conical shell or casingprovided about the periphery of the trip member, which is designed tobreak upon application of a load or pres sure in excess of apredetermined value. The trip member is preferably secured to the upperportion of the housing in a tightly sealed manner, for example, bywelding or the like, along the rim of the conical casing. The shank ofthe percussion pin is guided within a central bore provided in the tripmember.

Generally, the pressure translating member incorporates a toroidal orannular bead which engages the leaf spring during the triggering processuntil the tip of the percussion pin approximately impinges upon thepercussion explosive charge of the detonator cap, the contact betweenthe member and the leaf spring being precisely symmetrical about thecentral axis thereof. In accordance with this conventional arrangement,a precisely symmetrical bending of the spring is achieved; thus, whenthe spring flexes, in a snap-like manner, all portions of the springmove simultaneously, with the result that the percussion pin isdepressed into the percussion explosive charge in a precisely verticaldirection.

The conventional fuses described immediately above have been found to begenerally satisfactory when used in conjunction with tank mines having anormal pressure lid. However, for various reasons, such as to preventaccidental detonation of a mine in the presence of extreme pressurewaves, as from a nuclear explosion, alternative constructions of tankmines are often employed, wherein a rocker lid is provided in place ofthe normal pressure lid. In mines of this type, the tilting or rockerlid system incorporates inherent forces of restoration which causes thelid to execute a rocking motion when passed over by a tracked vehicle,under the influence of each wheel rolling thereof. This rocking motionis translated by the central detonator system of the mine into verticalmotions in accordance with a predetermined translation ratio.

When employing mines having a rocker lid, the path traversed by theperipheral or rim portion of the rocker lid, in the vertical direction,may be sufficiently large, depending upon the translation ratio, todetonate the mine when the first wheel of a tracked vehicle traversesthe lid. However, if the displacement of the rim portion of the rockerlid is of a lesser magnitude than the critical value, the mine may notbe detonated, even though the specific pressure forces of a vehiclepassing over the lid might normally be sufficient to trigger the mine.In such cases, detonation failures may be traceable to unsuitablesurface conditions, to an improperly implanted mine (in a hole withoutsufficiently beveled edges), or merely to a light-weight construction oftracked vehicles.

Accordingly, it is an object of the present invention to provide anon-metallic mine pressure fuse of the type described above whichinsures detonation even when incorporated in a tank mine utilizing atilting or rocker lid.

Further, it is an object of the present invention to provide a fuse ofthe type described above which is responsive to a series of deflectionseach of which is of lesser magnitude than a predetermined criticalvalue.

Finally, it is an object of the present invention to provide a fuse ofthe type described hereinabove which can readily be incorporated withinconventional mines and detonating equipment therefore.

SUMMARY OF THE INVENTION The foregoing objects are accomplished, inaccordance with the present invention, by providing means within thefuse mechanism to accumulate the effects of a plurality of appliedimpulses, each of which, alone, would otherwise be insufficient forcausing detonation, which means produce detonation when the total of theindividual impulses exceeds the critical value. Since normal trackedvehicles include several wheels, each of which exerts a particularimpulse upon a mine fuse, the present invention contemplatesaccumulating the total effects of the relatively small individualimpulses to define an effective deflection path representing a total ofthe individual impulses, eventually causing detonation when theeffective path exceeds the predetermined critical value.

This accumulation is accomplished, in accordance with the presentinvention, by providing a detent arrangement between the trip member andthe pressure translating member and a second detent member between thepressure translating member and the upper portion of the housing. Thisdouble detent arrangement effectively provides for a locking of thepressure translating member in the position to which it has beendepressed by an individual impulse, while permitting the trip member toresume its original position relative to the upper portion of thehousing after transferring the effects of a non-critical impulse.

Thus, as the next wheel traverses the mine, the pressure pin is againdepressed, the deflection being added to the deflection produced by thefirst wheel and fully transmitted to the leaf spring. Thereafter, thetrip member is again returned to its initial position to transmit stillanother impulse. In this manner, depending upon the sensitivity of thelocking detents provided, a desired number of incremental deflectionscan be totaled to achieve a final critical deflection path resulting indetonation of the mine.

It should be noted, however, that the novel arrangement contemplated bythe present invention does not preclude detonation of the mine inresponse to the first wheel of the tracked vehicle. Thus, if a mineprovided with a fuse as contemplated by the present invention istraversed by a tracked vehicle causing a sufficient deflection totraverse the required number of detents, the deflection can be fullyeffective to cause detonation upon the impulse of the first wheel.

Preferably, the pressure translating member is provided with an annularrecess between inner and outer circumferential walls on which thelocking detents are disposed, so that the annular walls can yieldelastically in a corresponding manner when the trip member is displaced.

In order to enhance the restoring force of the spring, the trip membercan be further supported, at the upper portion of the housing, by meansof additional spring arms. Toward this end, the bearing surface for thespring arms provided on the upper portion of the housing, can be of aconical configuration.

DETAILED DESCRIPTION OF THE DRAWING The foregoing objects, features andadvantages of the present invention will become more readily apparentfrom a consideration of the detailed description hereinbelow, whenconsidered in conjunction with the accompanying drawing, which is aschematic sectional view of a non-metallic mine pressure fuseconstructed in accordance with one embodiment of the present invention.

The non-metallic mine pressure fuse or detonator constructed inaccordance with the present invention includes an upper housing portion1 and a lower housing portion 2, which are threadedly engaged andsealingly cemented together. Between the upper housing portion 1 and thelower housing portion 2, the peripheral surface of a leaf spring 8,oriented in the direction of the upper housing portion 1, is retained. Apercussion pin is retained, by its neck-like constriction 14, bycentrally-provided aperture in leaf spring 8. A detonator cap orpercussion explosive charge 9 is disposed within a recess of lowerhousing portion 2. A trip member 4 is attached, by means of conicaljacket 27, to which it is glued, to upper housing portion 1. Percussionpin 5 is disposed within a central bore provided in trip member 4.

Between trip member 4 and upper housing portion 1, a pressure or forcetranslating member 6a is disposed. Member 6a is provided, at itslowermost surface, with a toroidal projection 13, which can engage, in asymmetric manner, with the upper surface of leaf spring 8.

6 Pressure translating member 6a IS constructed as a stop member and isprovided with an annular recess 35. The annular wall 36 includes detentteeth 37 on the circumferential surface thereof facing the correspondingsurface of trip member 4. Detent teeth 37 serve to block movement oftrip member 4 in the direction of percussion explosive charge 9. Tripmember 4 is provided, on its outer circumferential surface, with teeth38 having a configuration corresponding to and adapted to engage withdetent teeth 37.

The outer annular wall 39 of pressure translating member 6a is providedwith ring-shaped teeth 40 on the upper circumferential surface, whichteeth serve to prevent displacement of member 6a in a direction oppositeto the direction of detonator cap 9. The ringshaped teeth 40 cooperatewith correspondinglyshaped teeth 41 provided on the opposingcircumferential surface of upper housing portion 1.

Additionally, trip member 4 is provided with arms, or a disk-like member42, which guides the trip member 4 with respect to upper housingportion 1. The arms 42 engage within a conically-shaped recess 43 ofupper housing portion 1.

In the ready position of the mine pressure fuse illustrated, thepressure translating member 6a is in its uppermost position and abutsagainst an annular projection of the upper housing portion, whereas thetrip member 4 is in its lowermost position with respect to theengagement of its annular teeth 38 with detent teeth 37. As individualimpulses of a relatively small magnitude are applied to trip member 4,the pressure translating member 6a is, in each instance, displaceddownwardly along the locking detents 41 in increments of one or moreteeth, depending upon the magnitude of the impulse. Of course, member 6ais effectively blocked from a return upward displacement by thecooperating teeth 40 and 41.

The restoring force of the leaf spring, until the flexing position ofthe spring has been reached, operates to return trip member 4 upwardlyin increments of one or more teeth so that trip member 4 is alwaysreturned to its uppermost initial position. Eventually, the additioneffect of the individual impulses applied, afforded by the fusecontemplated by the present invention, results in a position beingattained wherein a relatively small incremental impulse applied to tripmember 4 will serve to cause leaf spring 8 to be flexed downwardly, thuspermitting percussion pin 5 to penetrate into detonator cap 9.

It should be noted that the external dimensions of a conventional fuseneed not be altered by the particular construction of the pressuretranslating member 6a contemplated by the present invention. Thus, themine pressure fuse contemplated by the present invention can beincorporated, as desired, within mines provided with either aconventional pressure lid or rocker lid.

While the present invention has been disclosed with reference to but asingle specific embodiment, it is to be clearly understood that thescope of the invention is in no way limited to the specific detailsthereof, but is susceptible of numerous changes and modifications aswould be apparent to one with normal skill in the pertinent technology.

What is claimed is:

l. A non-metallic mine pressure fuse, comprising:

housing means,

leaf spring means retained, at the peripheral surface thereof, by saidhousing means, the central portion of said leaf spring means projectingupwardly in the initial unbiased position thereof and defining acentrally-disposed aperture therein, percussion pin means supported foraxial displacement relative to said housing means, including means foroperatively connecting said pin means with said leaf spring means foraxial displacement together therewith, detonating cap means disposedwithin said housing means so as to receive the tip of said pin meansupon downward flexing of said leaf spring means,

trip means projecting from the upper surface of said housing means andsupported for axial displacement relative thereto a distancecorresponding to an applied force, .7

pressure translating means interposed, within said housing means,between said trip means and said leaf spring means, said pressuretranslating means being displaceable in the axial direction to translatea downward axial displacement of said trip means into a downward axialdisplacement of unretained portions of said leaf spring meanscorresponding to the magnitude of the force applied, and

detent on said housing and on said pressure translating means permittingthe downward axial displacement of said pressure translating meansrelative to said housing means and precluding upwardly directed axialdisplacement of said pressure translating means upon removal of saidforce so that said leaf spring can be fixed in positions intermediateits initial unbiased condition and the position wherein said detonatingcap receives said pin means whereby said fuse can be activated by thecumulation of successive forces each individually insufficient.

2. A mine pressure fuse according to claim 1, wherein said detent meansincludes cooperating sets of teeth provided on mating surfaces of saidhousing means and said pressure translating means, permitting downwardlydirected axial displacement of said pressure translating means relativeto said housing means, but effectively blocking correspondingdisplacement in an upward direction.

3. A non-metallic mine pressure fuse, comprising:

housing means,

leaf spring means retained, at the peripheral surface thereof, by saidhousing means, the central portion of said leaf spring means projectingupwardly in the initial unbiased position thereof and defining acentrally-disposed aperture therein,

percussion pin means supported for axial displacement relative to saidhousing means, including means for operatively connecting said pin meanswith said leaf spring means for axial displacement together therewith,

detonating cap means disposed within said housing means so as to receivethe tip of said pin means upon downward flexing of said leaf springmeans, trip means projecting from the upper surface of said housingmeans and supported'for axial displacement relative thereto a distancecorresponding to an applied force,

pressure translating means interposed, within said housing means,between said trip means and said leaf spring means, said pressureranslating means tive to saidhousing means and precludingupwardlydirected axial displacement of said pressure translating means uponremoval of said force so that said leaf spring can be fixed in positionsintermediate its initial unbiased condition and the position whereinsaid detonating cap receives said pin means whereby said fuse can beactivated by the cumulation of successive forces each individuallyinsufficient, said detent means including cooperating sets of teethprovided on mating surfaces of said housing means and said pressuretranslating means and further including cooperating sets of teethprovided on mating surfaces of said trip means and said pressuretranslating means permitting upwardly directed axial displacement ofsaid trip means relative to said pressure translating means buteffectively blocking corresponding relative displacement in a downwarddirection.

4. A mine pressure fuse according to claim 3, wherein said housing meansincludes an upper housing portion and a lower housing portion threadedlyand sealing engaged therewith, said peripheral surface of said leafspring means being retained between said upper housing portion and saidlower housing portion.

5. A mine pressure fuse according to claim 4, wherein said meansoperatively connecting said pin means with said leaf spring meansincludes a constricted portion of said pin means disposed within saidaperture of said leaf spring means.

6. A mine pressure fuse according to claim 3, wherein said pressuretranslating means includes two annularly extending wall members definingan annular recess therebetween.

7. A mine pressure fuse according to claim 3, wherein said trip means isconnected with said housing means by a conical jacket means, said tripmeans being glued to said conical jacket means.

8. A mine pressure fuse according to claim 7, further comprisingdisk-shaped bearing means of conical configuration, guiding said tripmeans for axial displacement relative to said housing means.

9. A mine pressure fuse according to claim 7, further comprisingradially oriented bearing arm means guiding said trip means for axialdisplacement relative to said housing means.

1. A non-metallic mine pressure fuse, comprising: housing means, leafspring means retained, at the peripheral surface thereof, by saidhousing means, the central portion of said leaf spring means projectingupwardly in the initial unbiased position thereof and defining acentrally-disposed aperture therein, percussion pin means supported foraxial displacement relative to said housing means, including means foroperatively connecting said pin means with said leaf spring means foraxial displacement together therewith, detonating cap means disposedwithin said housing means so as to receive the tip of said pin meansupon downward flexing of said leaf spring means, trip means projectingfrom the upper surface of said housing means and supported for axialdisplacement relative thereto a distance corresponding to an appliedforce, pressure translating means interposed, within said housing means,between said trip means and said leaf spring means, said pressuretranslating means being displaceable in the axial direction to translatea downward axial displacement of said trip means into a downward axialdisplacement of unretained portions of said leaf spring meanscorresponding to the magnitude of the force applied, and detent on saidhousing and on said pressure translating means permitting the downwardaxial displacement of said pressure translating means relative to saidhousing means and precluding upwardly-directed axial displacement ofsaid pressure translating means upon removal of said force so that saidleaf spring can be fixed in positions intermediate its initial unbiasedcondition and the position wherein said detonating cap receives said pinmeans whereby said fuse can be activated by the cumulation of successiveforces each individually insufficient.
 2. A mine pressure fuse accordingto claim 1, wherein said detent means includes cooperating sets of teethprovided on mating surfaces of said housing means and said pressuretranslating means, permitting downwardly directed axial displacement ofsaid pressure translating means relative to said housing means, buteffectively blocking corresponding displacement in an upward direction.3. A non-metallic mine pressure fuse, comprising: housing means, leafspring means retained, at the peripheral surface thereof, by saidhousing means, the central portion of said leaf spring means projectingupwardly in the initial unbiased position thereof and defining acentrally-disposed aperture therein, percussion pin means supported foraxial displacement relative to said housing means, including means foroperatively connecting said pin means with said leaf spring means foraxial displacement together therewith, detonating cap means disposedwithin said housing means so as to receive the tip of said pin meansupon downward flexing of said leaf spring means, trip means projectingfrom the upper surface of said housing means and supported for axialdisplacement relative thereto a distance corresponding to an appliedforce, pressure translating means interposed, within said housing means,between said trip means and said leaf spring means, said pressuretranslating means being displaceable in the axial direction to translatea downward axial displacement of said trip means into a downward axialdisplacement of unretained portions of said leaf spring meanscorresponding to the magnitude of the force applied, and detent meanspermitting the downward axial displacement of said pressure translatingmeans relative to said housing means and precluding upwardly-directedaxial displacement of said pressure translating means upon removal ofsaid force so that said leaf spring can be fixed in positionsintermediate its initial unbiased condition and the position whereinsaid detonating cap receives said pin means whereby said fuse can beactivated by the cumulation of successive forces each individuallyinsufficient, said detent means including cooperating sets of teethprovided on mating surfaces of said housing means and said pressuretranslating means and further including cooperating sets of teethprovided on mating surfaces of said trip means and said pressuretranslating means permitting upwardly-directed axial displacement ofsaid trip means relative to said pressure translating means buteffectively blocking corresponding relative displacement in a downwarddirection.
 4. A mine pressure fuse according to claim 3, wherein saidhousing means includes an upper housing portion and a lower housingportion threadedly and sealing engaged therewith, said peripheralsurface of said leaf spring means being retained between said upperhousing portion and said lower housing portion.
 5. A mine pressure fuseaccording to claim 4, wherein said means operatively connecting said pinmeans with said leaf spring means includes a constricted portion of saidpin means disposed within said aperture of said leaf spring means.
 6. Amine pressure fuse according to claim 3, wherein said pressuretranslating means includes two annularly extending wall members definingan annular recess therebetween.
 7. A mine pressure fuse according toclaim 3, wherein said trip means is connected with said housing means bya conical jacket means, said trip means being glued to said conicaljacket means.
 8. A mine pressure fuse according to claim 7, furtHercomprising disk-shaped bearing means of conical configuration, guidingsaid trip means for axial displacement relative to said housing means.9. A mine pressure fuse according to claim 7, further comprisingradially-oriented bearing arm means guiding said trip means for axialdisplacement relative to said housing means.